1.2.Â Welcome to FreeBSD!

FreeBSD is a 4.4BSD-Lite based operating system for Intel (x86
and ItaniumÂ®), AMD64, Sun UltraSPARCÂ® computers. Ports to
other architectures are also underway. You can also read about
the history of FreeBSD, or the
current release. If you are
interested in contributing something to the Project (code,
hardware, funding), see the Contributing
to FreeBSD article.

1.2.1.Â What Can FreeBSD Do?

FreeBSD has many noteworthy features. Some of these
are:

Preemptive multitasking with dynamic priority adjustment to ensure
smooth and fair sharing of the computer between
applications and users, even under the heaviest of
loads.

Multi-user facilities which allow many people to use a FreeBSD system
simultaneously for a variety of things. This means, for
example, that system peripherals such as printers and tape
drives are properly shared between all users on the system
or the network and that individual resource limits can be
placed on users or groups of users, protecting critical
system resources from over-use.

Strong TCP/IP
networking with support for industry standards such as
SCTP, DHCP, NFS, NIS, PPP, SLIP, IPsec, and IPv6. This
means that your FreeBSD machine can interoperate easily with
other systems as well as act as an enterprise server,
providing vital functions such as NFS (remote file access)
and email services or putting your organization on the
Internet with WWW, FTP, routing and firewall (security)
services.

Memory protection ensures that applications (or users) cannot
interfere with each other. One application crashing will
not affect others in any way.

The industry standard
X Window System (X11R7) can provide a graphical user
interface (GUI) on any machine and comes with full
sources.

Binary compatibility with many
programs built for Linux, SCO, SVR4, BSDI and
NetBSD.

Thousands of ready-to-run
applications are available from the FreeBSD
ports and
packages collection. Why search the
net when you can find it all right here?

Thousands of additional and
easy-to-port applications are
available on the Internet. FreeBSD is source code compatible
with most popular commercial UNIXÂ® systems and thus most
applications require few, if any, changes to
compile.

Demand paged virtual
memory and “merged VM/buffer cache”
design efficiently satisfies applications with large
appetites for memory while still maintaining interactive
response to other users.

SMP support for machines with multiple
CPUs.

A full complement of C
and C++
development tools.
Many additional languages for advanced research
and development are also available in the ports and
packages collection.

Source code for the entire system means you have the
greatest degree of control over your environment. Why be
locked into a proprietary solution at the mercy of your
vendor when you can have a truly open system?

Extensive online
documentation.

And many more!

FreeBSD is based on the 4.4BSD-Lite release from Computer
Systems Research Group (CSRG) at the University of California at Berkeley, and
carries on the distinguished tradition of BSD systems
development. In addition to the fine work provided by CSRG,
the FreeBSDÂ Project has put in many thousands of hours in
fine tuning the system for maximum performance and reliability
in real-life load situations. FreeBSD offers performance and
reliability on par with commercial offerings, combined with
many cutting-edge features not available anywhere else.

The applications to which FreeBSD can be put are truly
limited only by your own imagination. From software
development to factory automation, inventory control to
azimuth correction of remote satellite antennae; if it can be
done with a commercial UNIXÂ® product then it is more than
likely that you can do it with FreeBSD too! FreeBSD also benefits
significantly from literally thousands of high quality
applications developed by research centers and universities
around the world, often available at little to no cost.
Commercial applications are also available and appearing in
greater numbers every day.

Because the source code for FreeBSD itself is generally
available, the system can also be customized to an almost
unheard of degree for special applications or projects, and in
ways not generally possible with operating systems from most
major commercial vendors. Here is just a sampling of some of
the applications in which people are currently using
FreeBSD:

Internet Services: The robust
TCP/IP networking built into FreeBSD makes it an ideal
platform for a variety of Internet services such
as:

World Wide Web servers
(standard or secure [SSL])

IPv4 and IPv6 routing

Firewalls
and NAT
(“IP masquerading”) gateways

FTP servers

Electronic Mail servers

And more...

Education: Are you a student of
computer science or a related engineering field? There
is no better way of learning about operating systems,
computer architecture and networking than the hands on,
under the hood experience that FreeBSD can provide. A number
of freely available CAD, mathematical and graphic design
packages also make it highly useful to those whose primary
interest in a computer is to get
other work done!

Research: With source code for
the entire system available, FreeBSD is an excellent platform
for research in operating systems as well as other
branches of computer science. FreeBSD's freely available
nature also makes it possible for remote groups to
collaborate on ideas or shared development without having
to worry about special licensing agreements or limitations
on what may be discussed in open forums.

Networking: Need a new
router? A name server (DNS)? A firewall to keep people out of your
internal network? FreeBSD can easily turn that unused
PC sitting in the corner into an advanced router with
sophisticated packet-filtering capabilities.

Embedded: FreeBSD makes an
excellent platform to build embedded systems upon.
With support for the ARMÂ®, MIPSÂ® and PowerPCÂ®
platforms, coupled with a robust network stack, cutting
edge features and the permissive BSD
license FreeBSD makes an excellent foundation for
building embedded routers, firewalls, and other
devices.

Desktop: FreeBSD makes a
fine choice for an inexpensive desktop solution
using the freely available X11 server.
FreeBSD offers a choice from many open-source desktop
environments, including the standard
GNOME and
KDE graphical user interfaces.
FreeBSD can even boot “diskless” from
a central server, making individual workstations
even cheaper and easier to administer.

Software Development: The basic
FreeBSD system comes with a full complement of development
tools including a full
C/C++
compiler and debugger suite.
Support for many other languages are also available
through the ports and packages collection.

FreeBSD is available to download free of charge, or can be
obtained on either CD-ROM or DVD. Please see
AppendixÂ A, Obtaining FreeBSD for more information about obtaining
FreeBSD.

1.2.2.Â Who Uses FreeBSD?

FreeBSD's advanced features, proven security, predictable
release cycle, and permissive license have led to its use as a
platform for building many commercial and open source appliances,
devices, and products. Many of the world's largest IT
companies use FreeBSD:

Apache - The Apache Software Foundation runs most of
its public facing infrastructure, including possibly one
of the largest SVN repositories in the world with over 1.4
million commits, on FreeBSD.

Citrix - The NetScaler line of security appliances
provide layer 4-7 load balancing, content caching,
application firewall, secure VPN, and mobile cloud network
access, along with the power of a FreeBSD shell.

Dell
KACE - The KACE system management appliances run
FreeBSD because of its reliability, scalability, and the
community that supports its continued development.

Experts
Exchange - All public facing web servers are powered
by FreeBSD and they make extensive use of jails to isolate
development and testing environments without the overhead
of virtualization.

Isilon - Isilon's enterprise storage appliances
are based on FreeBSD. The extremely liberal FreeBSD license
allowed Isilon to integrate their intellectual property
throughout the kernel and focus on building their product
instead of an operating system.

iXsystems - The TrueNAS line of unified storage
appliances is based on FreeBSD. In addition to their
commercial products, iXsystems also manages development of
the open source projects PC-BSD and FreeNAS.

Juniper - The JunOS operating system that powers all
Juniper networking gear (including routers, switches,
security, and networking appliances) is based on FreeBSD.
Juniper is one of many vendors that showcases the
symbiotic relationship between the project and vendors of
commercial products. Improvements generated at Juniper
are upstreamed into FreeBSD to reduce the complexity of
integrating new features from FreeBSD back into JunOS in the
future.

McAfee - SecurOS, the basis of McAfee enterprise
firewall products including Sidewinder is based on
FreeBSD.

NetApp - The Data ONTAP GX line of storage
appliances are based on FreeBSD. In addition, NetApp has
contributed back many features, including the new BSD
licensed hypervisor, bhyve.

Netflix - The OpenConnect appliance that Netflix
uses to stream movies to its customers is based on FreeBSD.
Netflix has made extensive contributions to the codebase
and works to maintain a zero delta from mainline FreeBSD.
Netflix OpenConnect appliances are responsible for
delivering more than 32% of all Internet traffic in North
America.

Sandvine - Sandvine uses FreeBSD as the basis of their
high performance realtime network processing platforms
that make up their intelligent network policy control
products.

Sony - The PlayStation 4 gaming console runs a
modified version of FreeBSD.

Sophos - The Sophos Email Appliance product is based
on a hardened FreeBSD and scans inbound mail for spam and
viruses, while also monitoring outbound mail for malware
as well as the accidental loss of sensitive
information.

Spectra
Logic - The nTier line of archive grade storage
appliances run FreeBSD and OpenZFS.

The Weather
Channel - The IntelliStar appliance that is installed
at each local cable providers headend and is responsible
for injecting local weather forecasts into the cable TV
network's programming runs FreeBSD.

Verisign - Verisign is responsible for operating the
.com and .net root domain registries as well as the
accompanying DNS infrastructure. They rely on a number of
different network operating systems including FreeBSD to
ensure there is no common point of failure in their
infrastructure.

Voxer - Voxer powers their mobile voice messaging
platform with ZFS on FreeBSD. Voxer switched from a Solaris
derivative to FreeBSD because of its superior documentation,
larger and more active community, and more developer
friendly environment. In addition to critical features
like ZFS and DTrace, FreeBSD also offers
TRIM support for ZFS.

WhatsApp - When WhatsApp needed a platform that would
be able to handle more than 1 million concurrent TCP
connections per server, they chose FreeBSD. They then
proceeded to scale past 2.5 million connections per
server.

Wheel
Systems - The FUDO security appliance allows
enterprises to monitor, control, record, and audit
contractors and administrators who work on their systems.
Based on all of the best security features of FreeBSD
including ZFS, GELI, Capsicum, HAST, and
auditdistd.

FreeBSD has also spawned a number of related open source
projects:

BSD
Router - A FreeBSD based replacement for large
enterprise routers designed to run on standard PC
hardware.

FreeNAS - A customized FreeBSD designed to be used as a
network file server appliance. Provides a python based
web interface to simplify the management of both the UFS
and ZFS file systems. Includes support for NFS, SMB/CIFS,
AFP, FTP, and iSCSI. Includes an extensible plugin system
based on FreeBSD jails.